Imagine spinning a bucket filled with different kinds of matter. A solid will twirl along with the container because of the friction between the bucket and the material’s rigid lattice of atoms. A liquid, on the other hand, has less internal friction, so it will form a big vortex in the center of the bucket. (The exterior atoms rotate with the bucket while the inner ones lag behind.)

If you make certain liquids cold and sparse enough, their atoms begin interacting across longer distances, eventually linking together in one giant wave that flows perfectly without any friction. These so-called superfluids were first discovered in helium in 1937 by Russian(opens a new tab) and Canadian(opens a new tab) physicists.

Try spinning a bucket of superfluid, and it will remain at rest even as the bucket rotates around it. The superfluid still rubs against the bucket, but the material is totally impervious to friction until the container reaches a certain rotational speed. At this point, resisting the urge to rotate, the superfluid suddenly spawns a single quantum vortex — a whorl of atoms surrounding a column of nothingness that extends to the bottom of the bucket. Continue to speed up the container, and more of these perfect tornadoes will slither in from the rim.

An experimentalist's wet dream.